This invention relates to an original circulating and conveying device (hereinafter referred to as "an RDH" for Recycle Document Handler) for use with a copying machine.
The RDH is a device suitable for continuously handling either a number of original documents or a long-sided original, which has a wide range of applicability. Therefore, the RDH is extensively employed as an original handling device for high-grade and large document copying machines.
The invention relates to an improvement in an RDH of the type in which a stationary optical system is provided to mainly handle a long size original, such as a drawing, and in which the original is scanned and exposed while being conveyed.
A drawback accompanying a conventional RHD is that the efficiency is considerably low in the case where only one original much shorter than the length of the RHD original circulating path is inserted (this is the case that occurs most frequently in a generally used copying machine) and a number of copies are obtained by continually recirculating the original through a path which is much longer than necessary. This had led to the development of a variable length RDH disclosed in copending and commonly assigned U.S. patent application Ser. No. 332,777, the disclosure of which is herein incorporated by reference. In such a system, the size of the original is measured and the circulation path length is controlled in accordance with the document size.
The RDH of this type is disadvantageous in that the length of an original to be handled is limited, and if an original longer than the limit value is inserted, it is liable to cause the RDH to jam. Further, a multitude of detecting elements are required to detect the document size.